This application claims priority to Japanese Patent Application JP 2000-186810, and the disclosure of that application is incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
The present invention relates to an optical disc in conformity with so-called zone constant angular velocity (ZCAV) system, an access method of the optical disc and a drive of the optical disc.
2. Description of the Related Art
As a recording format of an optical disc, a constant linear velocity system (hereinafter, referred to as xe2x80x9cCLV systemxe2x80x9d) and a constant angular velocity system (hereinafter, referred to as xe2x80x9cCAV systemxe2x80x9d) are conventionally well known.
The CLV system is a system in which a spindle motor is controlled so that rotational speeds thereof are inversely proportional to radii of tracks provided on an optical disc. In the CLV system, linear velocities of tracks to be recorded or reproduced become constant at any position on the optical disc, and the sector lengths and the recording/replaying frequencies of the tracks become constant throughout the whole gamut of the optical disc, and consequently the recording capacity of the optical disc can be enlarged. However, the CLV system has a problem such that the circuit system implementing the system becomes complex.
On the other hand, the CAV system is a system in which the rotations of a spindle motor and the recording/replaying frequencies used in the system are severally made to be constant, and thereby the circuit system implementing the CAV system can be simplified. However, because density of the data that can be recorded on the most inside track is small, the recording capacity of the whole optical disc becomes small.
For resolving the problem of recording capacity in the CAV system, the ZCAV system was proposed. The ZCAV system has the following features. That is, the ZCAV system makes most of the advantage of the CAV system that the rotation control is easy, and divides the whole recording area of an optical disc into a plurality of zones in a radius direction and increases the recording/replaying frequency in each zone by stages from the inner periphery side to the outer periphery side of the optical disc, and thereby increases the recording capacity of the optical disc.
FIGS. 7A and 7B are views for illustrating a recording mode of an optical disc in conformity with the ZCAV system. As shown in FIG. 7A, the whole recording area of the optical disc is divided into a plurality of zones, e.g. four zones Za-Zd in the example of the figure, in a radius direction. The disc rotational speed in each of the zones Za-Zd is controlled in conformity with the CAV control, and a recording/replaying frequency of each of the zones Za-Zd is made to be a prescribed constant frequency within the zone. However, the outer the zone is situated, the faster the rotational speed of the zone becomes and the higher the recording/replaying frequency of the zone becomes, and further the faster the accessing speed to the zone also becomes.
Then, in a plurality of tracks in each zone, a plurality of sectors, namely sectors Sa-Sd in the figure, are formed so as to align in radius directions.
As shown in FIG. 7B, in the leader Ga of each sector, a servo pit for tracking is formed, and address information is previously formatted (pre-pit) therein. Angle intervals of the formed pre-format parts in the respective sectors are fixed at every zone because the sectors are aligned in the radius directions at every zone as described above. Moreover, data is recorded in the data area Gd in each sector.
Incidentally, because the pre-format parts are not aligned in a radius direction at the boundaries in two adjoining zones, no-recording area ranging at least two tracks are formed lest address information should be mixed with recording signals or reproducing signals to exert a bad influence on the operation of a phase-locked loop (PLL) or other elements when an adjoining track in another zone is scanned.
Now, for making an optical disc of the ZCAV system have a larger recording information quantity, an optical disc was proposed in which lands Ln and grooves GR, both having substantially the same width and adjoining to each other and further being used as recording tracks severally, were spirally formed as shown in FIG. 8.
In this case, address information is recorded in order that the address information can be utilized by both of the groove tracks and the land tracks. FIG. 9 shows one example of recording of the address information, in which two pieces of address information ID1, ID2 are recorded by pre-pitting at the positions shifted like a check pattern in a direction perpendicular to a groove track GrT and a land track LnT.
In this case, the two pieces of address information ID1, ID2 are recorded so that, when a light beam scans the groove track GrT, the two pieces of address information ID1, ID2 become equal in each pre-format part and the two pieces of address information ID1, ID2 change continuously at every pre-format part.
Consequently, when a light beam scans the groove track GrT, the two pieces of address information ID1, ID2 that are equal to each other can successively be obtained from each pre-format part. On the other hand, when the light beam scans the land track LnT, the two pieces of the address information ID1, ID2 different from each other can be obtained from each pre-format part.
As described above, in the address areas of the groove tracks, the track address information is conventionally recorded so as to be continuous over the whole area of an optical disc, i.e. over a plurality of zones.
Accordingly, in the data recording method into such a kind of optical disc, an access method is adopted in which data is recorded in the groove tracks over all of the zones at first, and then the data is recorded in the land tracks from aspect of the track addresses continuity.
However, such an access method is very inefficient. That is, for example, in case of accessing from the outermost periphery side zone successively, when the recording to the groove track in the zone Za on the outermost periphery side has been completed, the zone is changed so that the groove track in the zone Zb, in which access speed is lower, on the inside of the zone Za, to which high speed accessing is possible, on the outermost periphery side, is accessed although vacant land tracks to which the data has not been recorded yet exist in the zone Za.
Moreover, at each time of the access to the groove tracks and the access to the land tracks, the change of a zone becomes necessary by the number of zones. Consequently, the access speed becomes slower owing to the large number of times of the changes.
Moreover, the correspondence between the addresses of the groove tracks and the addresses of the land tracks could conventionally not be distinguished only by looking at the track addresses, and some means for distinguishing between the groove tracks and the land tracks was necessary.
That is, if the addresses of the groove tracks and the addresses of the land tracks in each zone of an optical disc of this type are indicated by track addresses (or track numbers) and sector addresses (or sector numbers), they become ones as shown in FIG. 10.
As shown in FIG. 10, if the track numbers and the sector numbers are traced by the groove track or by the land track, the track numbers and the sector numbers are continues addresses, and then the track in each zone can be distinguished. However, the track numbers and the sector numbers of the groove tracks and the land tracks in the same zone become the same. Consequently, the sectors in the groove tracks and the sectors in the land tracks cannot be distinguished only by the track numbers and the sector numbers, and means for distinguishing the grooves and the lands becomes necessary.
An object of the invention is to provide an optical disc that can efficiently be accessed and both of the groove tracks and the land tracks of which can be distinguished only by means of their track numbers even if the optical disc uses both of the groove tracks and the land tracks and the pre-format of the same addresses is performed on both of the groove tracks and the land tracks. The present invention also aims to provide an access method of such an optical disc and a drive apparatus of such an optical disc.
According to one embodiment of the present invention, the foregoing and other objects and advantages are attained by an optical disc, which is divided into a plurality of zones in a radius direction, and on both of a land track and a groove track of which data can be accessed, and further on which pieces of address information are recorded so that a same piece of address information can be used for any tracks of the land track and the groove track, wherein the pieces of address information are recorded so that they are successively continuous addresses in each zone and they are discontinuous in order that an address jumping by addresses of a previous zone in an access order thereof becomes a forefront address of a zone next to the previous zone at a beginning of the zone next to the previous zone.
According to the optical disc having the aforesaid structure in accordance with the one embodiment of the present invention, the addresses of tracks between a certain zone and a previous zone thereof are made to be discontinuous by jumping by an amount of the addresses of the previous zone. Consequently, in the case where, after the access to, for example, a groove track in which address information is recorded is completed in the previous zone, next, the first address of a land track in the same zone is accessed, the aforesaid amount of jumped addresses can suppositionally be assigned as the addresses of the land tracks.
Then, if the addressing is set to move to a groove track in the next zone after the last address of the land tracks in a zone has been used, a suppositional addresses in the land tracks in the zone and the actual addresses in the groove tracks in the next zone become continuous, and consequently address administration becomes very easy to understand. Consequently, the efficient access operation in which a move to the next zone after all of the groove tracks and the land tracks in the same zone have been used can easily be performed.
Moreover, according to one embodiment of the present invention, an access method of an optical disc, which is divided into a plurality of zones in a radius direction, and on both of a land track and a groove track of which data can be accessed, and further on which pieces of address information are recorded so that a same piece of address information can be used for any track of the land track and the groove track, said pieces of address information being recorded so that they are successively continuous addresses in each zone and they are discontinuous in order that an address jumping by an amount of addresses of a previous zone in an access order thereof becomes a forefront address of a zone next to the previous zone at a beginning of the zone next to the previous zone, the method comprising the steps of: performing access to either of the land track and the groove track by means of the pieces of address information in each zone; returning to a first address position in a zone after an address in the either track becomes a last address of the zone; performing the access by recognizing an address being continued from a last address of the either track suppositionally on the pieces of address information as an address of another track of the land track and the groove track; and moving to a next zone after the address of the other track becomes a last address of the zone.
The access method having the aforesaid steps according to the one embodiment of the present invention, in each zone, accesses to, for example, a groove track at first, and then accesses to the first address of a land track in the same zone next after using the last address of the groove track in the zone.
In this case, the track addresses on the optical disc are set to be discontinuous between a certain zone and the next zone with a jump by an amount of the addresses of the certain zone, and addresses for the jumped amount can be assigned to the land tracks. Accordingly, the addresses of the land track are used by setting their addresses continuing from the last address of the groove tracks in the same zone suppositionally. Then, after the last address of the land track in the zone has been used, the access moves to the next zone.
Consequently, the access to be moved to the next zone after all of the groove tracks and the land tracks in a zone have been used becomes possible to be easily performed in correspondence with the track addresses.
As described above, according to embodiments of the present invention, recording in the groove tracks and the land tracks is possible, and addresses can be administrated only by means of two parameters concerning track addresses and sector addresses even in the case where addresses are shared among the groove tracks and the land tracks of an optical disc having the ZCAV format. Thereby, the efficient access can be performed.